Met Office issues yellow weather warning as rain forecast to move in tonight, and motorists warned to take care

Large parts of Wales have been put on flood alert as the nation's long heatwave comes to a soaking wet end.

Heavy rain and thunderstorms are forecast to sweep across Wales over the next two days, bringing the threat of flash flooding as the water falls on the sunbaked earth.

The first of the rainfall is expected to hit North Wales tonight, and will move over the rest of the country on Tuesday and Wednesday.

Natural Resources Wales have warned people travelling home from work - and particularly attending events like the Royal Welsh Show - to take extra care, with driving conditions expected to be difficult.

In pictures: Crowds enjoy the first day of the Royal Welsh Show in sunshine

A statement issued by Natural Resources Wales said: "Due to the recent warm weather the ground is particularly hard meaning water will run off more quickly into drainage systems.

"There is a risk that this cause roads to flood and drains, ditches and small streams to overflow."

No rain has fallen across most of Wales since the start of July, with temperatures on most days staying in the mid to high 20s.

But with an area of low pressure now moving in to replace the high pressure system responsible for the sunshine, the Met Office has issued a yellow weather warning for much of Wales, coming into force for north and eastern areas from 3pm on Monday afternoon, and for the whole country for the whole of Tuesday.

The Met Office's chief forecaster's assessment also warned of the possibility of high winds and even hail as a result of the storms.

The assessment said: "An area of low pressure is expected to increasingly interact with the plume of hot, humid air resident across parts of southern Britain.

"Whilst preceding days will have seen relatively isolated thunderstorms, the developing set-up on Tuesday and early Wednesday, provides the ingredients for more widespread and energetic storms.

"Large rainfall totals, falling in short periods (perhaps exceeding 50 mm in 3 hours) and onto hard-baked ground, may lead to flooding locally, with hail and gusty winds an additional possibility."

"As is common in such situations, not everywhere will catch the heaviest of the storms, and some places may well escape altogether."

WalesOnline is part of Media Wales, publisher of the Western Mail, South Wales Echo, Wales on Sunday and the seven Celtic weekly titles, offering you unique access to our audience across Wales online and in print.